Farm team to stardom: The evolution of two kid stars, Bridgit Mendler and Victoria Justice

AP file photosBridgit Mendler, left, and Victoria Justice are both moving up the ranks of kids television with their own shows.LOS ANGELES -- Get ready to meet Bridgit Mendler and Victoria Justice, the two biggest stars the world has never heard of — at least that segment of the planet that excludes anyone outside the ages of about 8 and 14.

But among that increasingly coveted "tween" demographic, the one that made superstars of Miley Cyrus and Zac Efron, Justice and Mendler's career arcs have been steadily rising for years.

Mendler, as almost any kid with a TV knows, was the cute vampire who dated David Henrie's socially inept wizard on "Wizards of Waverly Place." Justice was the equally cute upstart rival to Jamie Lynn Spears on "Zoey 101."

Now the two 17-year-olds are getting their own Sunday night sitcoms, Justice in "Victorious," which debuts at 8 p.m. EDT this weekend, and Mendler in "Good Luck Charlie," which airs just a half hour later and had its debut last weekend. And if the past success of their respective networks' star-making machinery is any indication (Disney for Mendler and Nickelodeon for Justice), both are poised to be kid TV's next big thing.

Mendler's character on "Good Luck Charlie" is determined to videotape every significant (i.e. comical) event in the life of her newborn sister, Charlie, while at the same time juggling typical teen problems like annoying brothers, overly protective parents and flaky boyfriends.

"Victorious" meanwhile, puts Justice in a performing arts high school whose wacky student body (populated by several young Broadway theater veterans) is capable of breaking into song and dance whenever the mood strikes.

The show's creator, Dan Schneider, says he began grooming the actress for just such a breakout role the moment he saw her audition to play second banana to Spears on "Zoey 101" nearly five years ago.

"You could tell from the first five seconds of the tape ... she was just meant to be in front of a camera," said Schneider, creator of such hugely popular kid shows as "Drake and Josh" and "iCarly."

At rival Disney, the feeling was the same when a 14-year-old Mendler arrived to audition for "Sonny With a Chance." The role would go to another tween idol, Demi Lovato, but Mendler wouldn't go unnoticed.

"Bridgit is a great example of ... us finding somebody, knowing that we wanted to do business with her and then waiting to find the perfect role," said Gary Marsh, chief creative officer and president of entertainment for Disney Channels Worldwide.

There seems to be a wealth of TV tween stars at the moment, raising the question is there room for two more. The Jonas Brothers have their own eponymous show, Miranda Cosgrove has become nearly a household name on "iCarly" and so has Selena Gomez on "Wizards of Waverly Place," their images plastered all over TV, on lunch boxes, backpacks, even the sides of buses.

But that doesn't mean networks like Disney and Nickelodeon can ever stop cranking out new kid stars, says media consultant Jonathan Taplin. The obvious reason: they grow up, as Cyrus, in her last year of "Hannah Montana," is quickly doing.

Some of them sometimes also cause embarrassment, as Spears did when she announced she was pregnant as the fourth season of "Zoey 101" was beginning. Or when a nude photo of Vanessa Hudgens surfaced on the Internet when she was starring opposite Efron in the "High School Musical" movies.

"They have to have backup," Taplin says of the networks. "It's the farm team. You give someone a supporting role in a series and if they're good they eventually get to be the star."

To prepare them, Disney puts them through something it calls Talent 101.

"We try and give them a kind of lay of the land of how their lives are about to change and what things they have to watch out for," Marsh says, adding the seminar advises them on security precautions they might take and how to behave in public and in front of the press.

Not that looming stardom seems to have had much of an impact so far on Mendler, who can appear self-assured beyond her years one moment, while discussing something like acting, then revert to a wide-eyed innocence when talking about getting her driver's license.

"I don't think it's something I can really prepare for," she says of fame, then, as if to make her point, snorts with laughter.

During a recent day on the set, "funny hat day," Mendler explains, she has arrived with her signature long, blond hair hidden under a floppy-eared Lilo and Stitch hat.

"I don't think people can take me seriously in this hat," she adds, giggling again, "But I like it."

Likewise, Justice remains sanguine.

"It's kind of surreal that I'm even sitting here now, kind of looking back on my past story," she says during a moment of reflection on the set of "Victorious."

Yes, she acknowledges, carrying a TV show is a big responsibility. But, hey, she's had other challenges in her life.

"I graduated high school!," she shrieks with delight. Then she raises her arms and adds, "YAAAY!"